Vertical bag form-fill-seal machines are an example of a form-fill-seal machine in which, conventionally, a bag that, while being formed, is filled with package contents such as food products, and hermetically sealed to package the contents. A bag form-fill-seal machine shapes a packaging material that is a film of sheet form into a cylindrical shape (tube shape) using a former and a tube, and seals the overlapping vertical edges of the tube-shaped packaging material with a longitudinal sealing mechanism. The interior of the tube-shaped packaging material is then filled with package contents, the top part of the bag and the bottom part of the bag are sealed by a transverse sealing mechanism, and then the transverse-sealed portions are cut across the center by a cutter. In a pillow form-fill-seal machine, the aforedescribed actions of forming bags and filling the bags with package contents are carried out continuously in alternating fashion.